A

The correct curve representing the magnetic induction (B) along the axis of a solenoid is shown in Option A.
Step 1: Begin by recalling that inside a long solenoid, the magnetic field is uniform and doesn't change with distance from the center.
Step 2: At the center of the solenoid, the magnetic induction is maximum and is given by the formula:
B = 0ni, where  is the permeability of free space, n is the number of turns per unit length, and i is the current.
Step 3: As you move away from the center towards the ends of the solenoid, the magnetic field strength decreases smoothly.
Step 4: This relationship creates a characteristic bell-shaped graph, as shown in Option A.
Therefore, the correct answer is Option A.